5191 (14) G. Silvestri, S.Gambino, M. Guainazzi, andR. Ercoli. J. Chem. SOC.,Dalton Trans., 2558 (1972). (15) N. A. Beach and H. B. Gray, J. Am. Chem. SOC.,80, 5713-5721 (1968). (16) R. Orbach, Proc. Phys. SOC.,London, 77, 821-826 (1961). (17) N. J. Hill, J. Chem. Soc., Faraday Trans. 2, 68, 427-434 (1972). (18) I. A. Miller and E. L. Offenbacher, Phys. Rev., 166, 269-278 (1968). (19) B. Bleaney and M. C. M. O'Brien, Proc. Phys. Soc., London, Sect. B, 29, 1216-1229 (1956). (20) K. W. H. Stevens, Proc. R. SOC.,London, Part A, 219, 542-555 (1953). (21) M. Gerloch and J. S.Miller, Prog. lnorg. Chem., 10, 17 (1968).
(22) H. Kamimura, J. Phys. SOC.Jpn., 11, 1171-1181 (1956). (23) T. M. Dunn, Trans. Faraday Soc., 57, 1441-1444 (1961). (24) R . M. Goiding, "Applied Wave Mechanics", Van Nostrand, London, 1969, Chapter 7. (25) K. H. Hausser, Z.Naturforsch. A, 16, 1190-1192 (1961). (26) G. Henrici-Olive, S. Olive, 2.Phys. Chem. (Frankfurtamkin), 56,223-231 (1967). (27) E. Konig, 2.Naturforsch. A, 19, 1139-1147 (1964). (28) B. R . McGarvey, J. Phys. Chem., 71, 51-67 (1967). (29) W. T. Oosterhuis and G. Lang, Phys. Rev., 138, 439-456 (1969)
The Heat Capacity, Conductivity, and Crystal Structure of Tetrathiafulvalenium 2,5-Diethyltetracyanoquinodimethane Arthur J. Schultz,lBGalen D. Stucky,*la Robert Craven,Ib Mark J. Schaffman,lb and Myron B. Salamonlb Contribution from the Department of Chemistry and Materials Research Laboratory, Uniuersity of Illinois, Urbana, Illinois 61801, and the Department of Physics and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801. Received August I 1 1975 I
Abstract: The single-crystal room temperature structure and measurements of the conductivity and heat capacity in the vicinity of the metal insulator transition have been determined for the pseudo-one-dimensional charge transfer salt-tetrathiafulvalenium 2,5-diethyltetracyanoquinodimethane (TTF-DETCNQ). The compound crystallizes in space group P1 with cell dimensions u = 13.654(4)A, b = 3.859 (1) A, c = 10.094(3)A, a = 97.00(2)O,p = 96.25(2)O,and y = 85.91 (2)'. The perpendicular interplanar distances along the segregated stacks are 3.598(1) A for T T F and 3.257 ( I ) 8, for DETCNQ. The metal insulator transition observed in the conductivity measurements in the b-axis direction is sharply defined by a peak in the heat capacity curve at I 1 1 K. Assuming a single band model, we estimate the density of states a t the Fermi surface to be 5.7 eV-I. The effect on the transition temperature of changes in the density of states, degree of charge transfer, and stacking distances are discussed.
One of the methods used in trying to understand the metal insulator transition in the highly conducting charge transfer salt TTF-TCNQ2 has been the study of chemically modified TTF-TCNQ compounds. The goal of these investigations has been to synthesize new materials with minimal structural changes so that the effects of crystal d i ~ o r d e r , intra~ - ~ and interchain coupling,6 ionization potential, and polarizability on the metal insulator transition and the high temperature conductivity of a series of crystals can be studied. The TTF-TTF interplanar distances in the one-dimensional systems which have been investigated are 3.47 A' or greater. This spacing is comparable to van der Waals distances associated with nonbonded interactions between organic groups, and it is not surprising that numerous derivatives of TTF8-I1 or TSFI2-I5(the selenium analogue of TTF) are known to form highly conducting complexes with TCNQ. The TCNQT C N Q interplanar spacing in TTF-TCNQ is 3.16 A.7 This is well below the van der Waals contact for even aromatic carbon atoms (-3.34 A) so that it can be expected that it will be much more difficult to obtain a closely stacked lattice and metallic behavior with substituted TCNQ. In fact, metallic behavior has not been previously reported for any derivatives of T C N Q , other than the very distantly related TNAP,I6 the 2,6-tetracyquinodimethanederivative of naphthalene. In this paper, we present the details of the room temperature structure and the specific heat and electrical conductivity in the vicinity of the metal insulator transition of the substituted T C N Q charge transfer salt tetrathiafulvalenium 2,5-diethyltetracyanoquinodimethane (TTF-DETCNQ). A preliminary screening of this and other substituted TCNQ complexes with TTF by GroffI7 of Du Pont Laboratories suggested
that a number of these materials are metallic. The fact that one can substitute organic groups on the TCNQ molecule and maintain cooperative behavior greatly expands the potential number of one-dimensional metallic systems which can be made. It also suggests the feasibility of forming conducting materials with T C N Q molecules attached to an organic polymeric backbone or forming donor-acceptor pairs joined together through chemical bonds. Further investigation of the low temperature crystal and molecular structure of TTFD E T C N Q is currently underway and will be reported in a subsequent publication.
Experimental Section Collection and Reduction of the X-Ray Data. The crystals used in this study were prepared by Drs. R. C. Wheland and E. L. Martin of the Du Pont Central Research Department18 and graciously supplied to us by Dr. L. J. Guggenberger. The long, black colored crystals appear as bundles of square, cross-sectioned fibers, rather than stacks of thin plates, as in TTF-TCNQ. Weissenberg and precession photographs revealed no systematic extinctions or other indications of symmetry. Therefore, a primitive cell for the triclinic space group PT was chosen with the b axis parallel to the needle axis of the crystal. The cell dimensions were refined from the angular diffractometer settings of 20 centered reflections and are u = 13.654(4)A, b = 3.859 ( 1 ) A, c = 10.094(3)A, CY = 97.00(2)",p = 96.25 (2)O,y = 85.91 (2)O,and- V = 523.8A3.The assumption of the centrosymmetric space group P1 is justified by the satisfactory agreement ultimately obtained. With one formula weight of TTF-DETCNQ per unit cell, the calculated density is 1.473g/cm3. Numerous crystals were examined on the diffractometer and found to be twinned or have very large mosaicities. The crystal finally selected for intensity measurements was mounted in a thin-walled glass
Schultz, Stucky, Craven, Schaffman, Salamon
/
TTF-DETCNQ
5192 Table I. Final Parameters for TTF-DETCNQ Atom
B (bz)b
Xa
Y
Z
-0.132 56 (5) 0.076 16 (5) 0.333 9 (2) 0.192 0 (2) -0.102 6 (2) -0.008 8 (2) -0.011 8 (2) 0.347 0 (2) 0.263 7 (2) 0.351 6 (2) 0.427 7 (2) 0.414 1 (2) 0.519 7 (2) 0.541 7 (2) 0.646 7 (2) -0.150 (2) 0.020 (2) 0.353 (2) 0.493 (2) 0.529 (2) 0.693 (2) 0.652 (2) 0.661 (2)
-0.0962 (2) -0.1191 (2) -0.5125 (6) -0.4810 (7) -0.1811 (9) -0.1927 (9) -0.0449 (7) -0.4173 (7) -0.4052 (7) -0.3180 (6) -0.1586 (6) -0.0827 (6) -0.0675 (6) -0.1366 (7) -0.0763 (8) -0.207 (6) -0.245 (6) -0.133 (6) 0.007 (6) -0.393 (6) -0.214 (6) -0.138 (6) 0.174 (7)
0.088 28 (7) 0.192 21 (7) 0.839 9 (2) 0.461 6 (2) 0.250 6 (3) 0.297 4 (3) 0.059 3 (2) 0.740 8 (3) 0.524 8 (2) 0.609 4 (2) 0.561 7 (2) 0.424 5 (2) 0.638 l ( 2 ) 0.783 2 (2) 0.846 7 (3) 0.307 (2) 0.374 (2) 0.379 (2) 0.837 (2) 0.787 (2) 0.792 (2) 0.938 (2) 0.854 (2)
c c
c c c c c c c
c c
c
c c c
3.0d 3.0 3.0 3.0 3.0 3.0 3.0 3.0
Anisotropic Thermal Parameters (X Atom S(1) S(2) N(1) N(2) C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11)
Pi1
P'Z
033
3.25 (4 3.79 (4 5.4 (2) 4.5 (2) 5.3 (2) 6.0 (2) 3.3 (1) 3.1 (1) 4.1 (2) 3.2 (1) 3.3 (1) 3.0 (1) 3.3 (1) 4.1 (2) 5.1 (2)
99.2 (9) 100.6 (8) 96 (2) 122 (3) 103 (3) 107 (3) 67 (2) 5 1 (2) 62 (2) 5 1 (2) 38 (2) 4 3 (2) 36 ( 2 ) 48 (2) 69 (3)
11.0 (1) 9.83 (9) 8.2 (3) 11.6 (3) 11.7 (4) 10.0 (4) 8.9 (3) 8.0 (3) 7.2 (3) 5.5 (3) 5.1 (3) 5.8 (3) 4.9 (2) 5.3 (3) 6.1 (3)
PI 3
012
-2.2 -0.9 -1.9 -6.8 -2.9 -1.0 -0.1 -1.9 -1.7 -0.9 -0.4 -1.3 -0.1 -1.4 -4.2
(1) (1) (5) (5) (7) (7) (5) (4) (5) (4) (4) (4) (4) (5) (6)
0.60 (5 -0.44 (5 1.8 (2) -0.7 (2) 2.7 (2) 0.1 (2) 0.0 (2) 1.0 (2) 1.2 (2) 0.5 (2) 0.7 (1) -0.1 (2) 0.5 (1) 0.1 (2) -0.9 (2)
p7.3
2.1 (2) 2.1 ( 2 ) 10.1 (7) 7.5 (8) 4.6 (9) 8.1 (9) -1.0 (7) 2.4 (7) 7.7 (7) 3.7 (6) 2.0 (6) 1.9 (6) 1.6 (5) 4.4 (6) 6.4 (7)
ax, y , z are fractional coordinates. b Isotropic temperature factor of the form exp(-E' sin' e / h ) .CAtoms refined anisotropically. dHydrogen temperature factors were not refined. e Anisotropic temperature factors of the form exp(-(h2p,, + k'p,, + /zp33+ 2 W , , + 2h1PI3+ 2k@,,)].
capillary and had approximate dimensions of 0.14 X 0.54 X 0.22 mm3. It showed some evidence of twinning in the a* direction, but its average mosaic spread as determined from narrow source-open counter w scans of several reflections was a reasonable 0.21 f 0.03'. The intensity data were collected by the 8-28 scan technique on a Picker FACS-I diffractometer using Mo KCYradiation with a graphite monochromator. Reflections were measured with calculated 28 values between 5 and 50' at a scan rate of 2'/min and with background counts of 10 s at each end of the scan. A symmetrical scan range of 1.8' in 28 was used with allowance made for Kal-Kai separation. The intensities of 1898 independent reflections were measured and corrected for Lorentz and polarization effects to yield a net of IFd values where F, is the observed structure factor amplitude. This led L 3u(Fo2).The standard derivations to 1261 reflections having FO2 u(FO2)were estimated according to the formula u(F02) = (Lp)-'[S
+ (BI + B2)(TS/2TB)2 + (0.021)2]'/2
where S and B I and B2 are the scan and background counts in times T , and TB,Lp is the Lorentz-polarization factor, and I is the integrated intensity. The data were not corrected for absorption ( p = 4.58 cm-I). Errors due to this neglect are estimated to be less than 1% of the measured intensities. Solution and Refinement of the Structure. The 253 normalized structure factors with I El 2 1.50 as calculated by FAMEL9were used in the M ~ ~ L T A N ~ Oprogram package to solve the structure by direct methods. The Fourier calculations based on the three sets of phases all having the highest figure of merit20 did not reveal any structural
Journal of the American Chemical Society
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98:17
/ August
fragments that made chemical sense. Finally, an E-map calculated from a set of phased IEl's with the second highest figure of merit yielded the two sulfur and three carbon atoms of the T T F molecule situated on the inversion center at (O,O,H).Refinement of the positional parameters using data with Fo2 5 3u(FO2)led to a weighted agreement factor R, (= (Zw(lFJ - IFd)2/zw IFd2)1/2) of 0.518. The function minimized in the least-squares refinements was Zw(1 FJ - IFd)2where the weights w were assigned as 2Fo/u(FO2).All the nonhydrogen atoms in the DETCNQ molecule were located by a sequence of least-squares refinements and difference Fourier syntheses. The neutral atomic scattering factors used in these refinements for the nonhydrogen atoms were those of Cromer and Waber.2I The sulfur atoms were treated for anomalous dispersion using the values of Af and Ay' tabulated by Cromer.22 For esthetic reasons, the origin was shifted such that the TTF was situated on the inversion center at (O,O,O) and the DETCNQ was situated on the inversion center at (1/2,0,1,$). Refinement of all the atoms with anisotropic thermal parameters and using all of the data (including F , = 0) led to agreement factors R (= ZllFoI - lFcl// Z I F o l ) and R, of 0.1 11 and 0.085, respectively. A difference Fourier revealed the positions of all eight independent hydrogen atoms. Surprisingly, the peaks on the Fourier map of the five ethyl hydrogen atoms were all higher than those for the ring hydrogen atoms, indicating minimal disorder in the ethyl substituent. Hydrogen atom scattering factors from Stewart et aLZ3 were used in refining the positional parameters of the hydrogen atoms. The parameters for all the atoms obtained from the final refinement with R = 0.070 and R , = 0.039 are presented in Table I. The final standard deviation of an observation of unit weight was 1.52 and the highest peak on the final difference Fourier was 0.407 e/A3, or about 57% of the average hydrogen atom in this structure. A tabulation of the 1898 observed and calculated structure factor amplitudes used in the final refinement is available.24 Heat Capacity Measurements. Heat capacity measurements were made on single crystals of this material using ac c a l ~ r i m e t r y . This ~~-~~ technique, which has been used successfully to characterize the thermal properties of TTF-TCNQ in the vicinity of its metal insulator t r a n s i t i ~ n ,has ~ ~ very , ~ ~ high sensitivity and can be used with very small (-10 pg) samples. Crystals, which were chosen on the basis of size and uniformity, were mounted (as shown in Figure 1) on a pair of thermocouples using silicon vacuum grease or GE703 1 cement. This thermocouple pair is formed by first spot welding lengths 25 Fm thick and 1.0.5 mm in width. The sample-thermocouple combination was heated by chopped pulses of light from a quartz-iodide lamp which was driven by a regulated dc current supply. One of the junctions of the crossed thermocouples detected the temperature oscillations of the sample with respect to the adjacent copper heat sink, while the other formed the cold junction of a cromel-alumel thermocouple with its hot junction at the ice point. The time averaged sample temperature was measured with this hot-cold thermocouple pair and a potentiometer. The magnitude of the thermal oscillations of the thermocouple-sample combination was measured with a lock-in amplifier phase locked directly to the chopper frequency. The magnitude of the temperature oscillations and the temperature of the sample were continuously recorded. The dynamic temperature excursions of the sample in this configuration can be described in terms of two time constants: T I , which characterizes the thermal coupling between the sample and its surroundings, and T 2 , the time for the sample to reach internal thermal equilibrium. In the present experiment, the major thermal coupling between the sample and the copper heat sink is provided by a helium exchange gas. When the angular frequency of the chopped light is such ~ 1, Le., when the sample comes to equilibrium with itself that W T 1 gives an average temperature rise of the sample of Po/Zk over the copper
18, 1976
5193
THERMOCOUPLE
-
2800 2725
-
2650
-
25 75 -
LIGHT
L+
a'
2500
U
Cu HEAT SINK
24252350
Figure 1. Experimental arrangement for specific heat measurements. The light comes from tungsten-iodide lamp, chopped by a mechanical chopper. The primary heat flow is along a line from right to left. heat sink with an oscillatory part CdT,,/dT = P o s ( ? ) / 2 .For small oscillations, C ( T ) is approximately constant and the above equation can be integrated to give a triangular wave form of amplitude 1 Tad = Po/2nwC. The inverse of the temperature oscillations is directly proportional to the heat capacity of the sample. Although the exact time constants are not known a priori, the correct operating range can be found by measuring the amplitude of the triangular temperature oscillations as a function of the chopping frequency with a broad band amplifier. The operating frequency, in this case 9 Hz, is chosen to be well within the region where I Tad a 1/ w . Using known thermal conductivities of the gas and simultaneous measurement of the temperature offset, Po/2k, and the temperature oscillations, it is possible to get an absolute measurement of the specific heat, but experimental limitations of low frequency preamplifier roll-off and small dc voltage measurements limit the accuracy of this number. We have chosen instead to calibrate the specific heat relative to dc measurements made on bulk samples of TTF-TCNQ. We expect that due to the structural similarity of these two systems the large lattice background will be within the 10% accuracy of the absolute measurements. Our relative accuracy is much higher, however, and allows us to characterize the thermal behavior of TTF-DETCNQ in the vicinity of its metal insulator phase transition. The specific heat of one sample of TTF-DETCNQ in the vicinity of its metal insulator phase transition is shown in Figure 2. This sample weighed 85 pg and was -2.5 mm long by 0.25 mm in length. The total lattice specific heat in this region is quite large, z 2 4 R (R = 8.317 J K-I mol-I), due to the large number of atoms per unit cell and contributions from low frequency optical phonon branches.3o The major feature of this specific heat data is the anomaly at 11 1 K. This anomaly occurs at the same temperature as the sharp change in the electrical conductivity and we associate it with a two- or three-dimensional ordering within the crystal which drives the metal insulator transition. N o other anomalies were observed between 15 and 300 K. In order to examine the transition of this sample more closely, we have subtracted a smooth lattice background, fit to the data above the transition temperature. The resulting data, along with that from another crystal of TTF-DETCNQ, which was 112 pg, are shown in Figure 3. The height of the specific heat anomaly is 2R to 3.5R. The entropy associated with the transition, obtained from direct numerical integration of only the data in this figure is 0.64R and 0.085R for the high peak and low peak, respectively. This does not include the contribution to the total entropy of the transition from temperatures below 99 K. Either a linear model for the specific heat in this region or a BCS-like formulation gives about 0.1R of entropy for this region if they are normalized to the 99 K data. Electrical Conductivity Measurements. Electrical conductivity measurements were made on single crystals of TTF-DETCNQ using a standard four probe dc measurement technique. The samples were mounted with Du Pont conductive silver composition no. 7941 on four 25 pm Auo 9CuO.l annealed alloy wires with care taken to surround the samples with the silver paint at the contacts to minimize the possibility of spurious current paths. The wires were loosely suspended on a mylar form in order to reduce the strain of the contacts upon cooling, but despite this precaution many samples cracked and became electrically discontinuous between room temperature and 200 K. Temperature measurement was made with a cromel-alumel thermocouple junction with the cold point being adjacent to the sample being measured and in thermal contact through an atmosphere of helium gas. Up to four samples were run at one time, each having its own thermometer. Data were taken by successively switching the constant measurement current from one sample to another and re-
#
P
2275-
/
22001 96
99
"
"
102
105
108
"
Ill
114
1
'
117
120
1
'
123 126
TEMPERATURE (K)
Figure 2. The specific heat in the vicinity of the metal insulator phase transition. )
0
4
25
t .* .*
I
96
105
102
99
108
114
Ill
120
I17
123
TEMPERATURE (K)
Figure 3. The specific heat of two samples minus the lattice specific heat background.
I
I
I
I
I
I
1
7
2
- 1.5 -.5
>
t
-0
a
--.5
8 0 3
--I
TEMPERATURE ( K )
Figure 4. The conductivity and log of the conductivity of one sample. The point of maximum slope in the plot of the conductivity vs. temperature is at the phase transition. cording the voltage through an analog to digital converter onto paper tape. Typical measurement currents were I 1 mA or I 1 A/cm2. Above the metal insulator phase transition, there was no evidence that the sample was being driven out of thermal equilibrium with the thermocouple junction by joule heating. The possible error in the absolute temperature displayed in this data and in the specific heat data is about i1 K. All thermocouple junctions were not separately calibrated against a standard resistance thermometer, but those which were showed variance of this magnitude. The results for one of the samples are displayed in Figure 4. This sample was 0.038 X 0.025 cm in cross section with the voltage contacts
Schultz, Stucky, Craven, Schaffman, Salamon
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TTF-DETCNQ
5194
n
n
n n
Figure 7. Projection of the overlap between neighboring T T F molecules viewed perpendicular to the molecular planes.
Figure 5. The crystal packing of TTF-DETCNQ as viewed parallel to the b axis.
Figure 8. Projection of the overlap between neighboring DETCNQ molecules viewed perpendicular to the molecular planes. Figure 6. The crystal packing of TTF-DETCNQ as viewed approximately perpendicular to the ab plane. 0.109 ( 5 ) cm apart. Both the conductivity and the logarithm of the conductivity are presented to allow comparison with the conductivities of TTF-TCNQ and to emphasize the region near the metal insulator phase transition. The shape of these data are typical for samples which survived cooling to 77 K. Above 200 K, the data are much noisier. It is possible that this is due to poor contacts since topographically bizarre current paths become more possible and more misleading3’ as the conductivity along the b axis of the crystal and the subsequent anisotropy become greater. This high temperature noise has also been seen in some preliminary measurements by workers a t the Du Pont laboratories.” The samples become too resistive for our measuring technique below 50 K, but no other anomalies were seen to this temperature.
Description of the Structure The crystal packing of the TTF-DETCNQ molecules is shown in Figures 5 and 6. Analogous to TTF-TCNQ,7 there are separate chains of TTF and D E T C N Q stacking parallel to the b axis. However, whereas in TTF-TCNQ the donors and acceptors each form a herringbone pattern in the bc plane, in TTF-DETCNQ all the TTF molecules and all the D E T C N Q molecules are crystallographically required to have the same orientations. This same type of packing is seen in crystals of TTF-TNAP.I6 Furthermore, the angle between the TTF and DETCNQ molecular planes (Table IV) is only 19.8”, as compared to 58.5” in TTF-TCNQ between nearest neighbors. The closest intermolecular contacts are those between N(2) -H(2), N(2)-.H( 1) and N ( l).-H( 1) a t values of 2.57,2.92, and 2.96 A, respectively. With the cyano groups of the DETCNQ molecule pointing inbetween the TTF molecules along the stack, the pairs of short nitrogen-sulfur contacts are 3.41 3 and 3.563 A for N ( 1)-S( 1) and 3.394 and 3.734 A for N ( 2 ) 4 ( 2 ) . There are no contacts between the ethyl hydrogens and the TTF molecules of less than 3.0 A. In addition. there Journal of the American Chemical Society
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98:17
is no evidence (vide ante) for a superlattice based on long range ordering of the ethyl groups. The angles between the b axis and the normals to the molecular planes are 21.2 and 32.4” for TTF and DETCNQ, respectively. The perpendicular interplanar distances are 3.598 (1) 8, for TTF and 3.257 (1) A for DETCNQ. These are significantly longer than the corresponding values of 3.473 ( 2 ) and 3.168 (2) 8, in TTF-TCNQ, but the TCNQ-TCNQ distance of 3.26 (1) A in N M P - T C N Q (N-methylphenazinium tetracyan~quinodimethane)~~ is the same as that for D E T C N Q in this structure. Projections perpendicular to the molecular planes along the stacks are shown in Figures 7 and 8. The TTF-TTF overlap appears to be identical with that in TTF-TCNQ, while the overlap of the D E T C N Q molecules is slightly less symmetric than that for the unsubstituted T C N Q due to the steric requirements of the ethyl groups. It is also apparent from Figure 8 that tris- or tetrasubstitution would make close T C N Q stacking sterically unfeasible, and that disubstitution in ortho positions could only be effective if every other T C N Q molecule along the stack was “flipped over”. The principal intermolecular bond angles and distances are given in Table I1 using the labeling scheme shown in Figures 9 and 10. Each molecule is situated’on a crystallographic center of inversion. In addition, if mmm symmetry is assumed for TTF, the related bond angles and distances agree to within one standard deviation. The bond angles in the T C N Q moiety are significantly distorted from m m m symmetry as shown in Figure 10. This is apparently a result of steric interaction between the ethyl group and the nearest cyano group with nonbonding contacts between C(4) and the methylene hydrogen atoms of 2.49 and 2.70 A. As shown in Table IV, C ( 10) is only 0.019 (3) A from the least-squares plane of the T C N Q moiety, while C ( 11) is 0.237 (3) A out of the plane. Since the bond distances are in good agreement in the
/ August 18, 1976
5195 Table 111. Rigid-Body Thermal Parameters for TTF-DETCNQ
Table 11. Principal Intramolecular Distances and Angles for TTF-DETCNQ
Atoms S(l)-C(l) S(2 )-C(2) C(l)-C(3) S(21-C (3) C(l)-C(2) C(3)-C(3)' C(1)-H(l) C(2)-H(2) N(l)-C(4) N(2)4(5) C(4)-C(6) C(5)-C(6) C(6)-C(7) C(7)4(8) C(7)4(9) C(8)-C(9)' C(9)-C(10) C(lO)-C(ll) C(8)-H(8) C(lO)-H(lOA) C(lO)-H(lOB) C(l1)-H(l1.A) C(ll)-H(llB) C(ll)-H(llC)
Distance, A CorObsd recteda 1.711 (3) 1.707 1.716 (3) 1.733 1.735 (3) 1.754 1.737 (3) 1.745 1.315 (4) 1.322 1.363 (5) 1.367 0.89 (2) 0.86 (2) 1.143 (3) 1.141 1.145 (3) 1.150 1.434 (3) 1.431 1.431 (3) 1.437 1.400 (3) 1.404 1.440 (3) 1.438 1.443 (3) 1.450 1.357 (3) 1.359 1.515 (3) 1.513 1.527 (4) 1.536 0.95 (2) 1.00 (2) 1.02 (2) 0.97 (2) 0.97 (2) 0.99 (2)
(a) TTF
Angle, Atoms deg S(l)-C(3)-C(3)' 122.2 (3) S(2)-C(3)-C(3)' 122.9 (3) S(l)-C(3)-S(2) 114.9 (1) C(1)-S(1)-C(3) 94.5 (1) C(2)-S(2)-C(3) 94.3 (1) C(l)-C(2)-S(2) 118.0 (2) C(2)-C(l)-S(l) 118.1 (2) N(l)-C(4)-C(6) 172.5 (3) N(2)-C(5)-C(6) 177.0 (4) C(4)-C(6)4(5) 110.3 (2) C(4)-C(6)-C(7) 128.4 (2) C(S)-C(6)-C(7) 121.3 (2) C(6)4(7)-C(8) 117.7 (2) C(6)-C(7)-C(9) 125.5 (2) 116.9 (2) C(8)-C(7)-C(9) C(7)
